We present a report of cardiac dilatation and symptomatic congestive heart failure in two patients receiving treatment with continuous ambulatory peritoneal dialysis (CAPD). Both patients had previous partial parathyroidectomies and persistent hypocalcemia prior to the development of a congestive cardiomyopathy. The hypocalcemia was unresponsive to treatment with activated vitamin D therapy; however, intravenous replenishment of the ionized serum calcium level was accompanied by improvement in cardiac functional parameters. In one of the two patients, chronic calcium repletion with high dialysate calcium was associated with significant improvement in cardiac symptoms and a decrease in left ventricular dilatation. These observations suggest that partial parathyroidectomy and associated hypocalcemia place patients on CAPD at increased risk of cardiac dysfunction.